In modern manufacturing methods, for the production of articles of enhanced strength, filament winding techniques are often employed. Such techniques involve the winding of high strength filaments disposed in a matrix of binder material about a form or mandrel of a shape generally corresponding to the required shape of the finished article, and then curing the matrix material. In the case of the manufacture of an elongate article such as an airfoil by such filament winding techniques, as the filaments are wound around the form, the form and filaments are reciprocally displaced relative to one another along the form's longitudinal or winding axis, thereby forming a plurality of layers of filamentary material, the filaments of each layer being angularly offset from the longitudinal and transverse axes of the form as well as from the filaments of adjacent layers. To achieve a continuous reciprocation of the filaments along the form as the filaments are wound thereon, it is the practice to employ turnarounds or winding rings at the ends of the form or the segment of the form being wound, overlying end turns of the various layers being constructed by winding the filaments over the edges and across an outer face of the winding ring while reversing the direction of the longitudinal displacement between the fibers and the form.
In the prior art, turnarounds functioning as described hereinabove, have been of circular or disc shapes, and the offset angle between filaments of adjacent layers and the spacing of individual filament turns within a single layer define a uniform, longitudinal reciprocating motion between the filaments and the form as the filaments are wound around the form. That is, the angular orientation and spacing of the filament turns in the various filamentary layers define, by way of the uniform reciprocating motion between the filaments and form, a multiplicity of secants of uniform length and disposition across the surface of the turnaround. If the form is of a cross sectional configuration wherein the cross sectional width is greater than the thickness, as is the case wherein the cross section is defined by an airfoil shape, it will be understood that in such prior art methods, substantial bridging occurs between the outer edge of the turnaround and the form surface or filamentary layers wound thereon. Such bridging is, of course, merely wasted material which must be removed from the finished article by subsequent machining operations or the like. Moreover, the bridging requires the turnaround to be spaced from the location of the end of the completed article. Thus, equipment used to wind the filaments on the form must be capable of travel in excess of that which would be required if such bridging were somehow avoided. It is, of course, appreciated that this excess travel capability adds to the size and cost of such winding equipment and therefore, the manufacturing costs of the finished article.